Ruby 1.9.1 is not compatible with Rails 3.0 Beta 4. Please install Ruby 1.9.2 RC1 instead. Here's a couple of links about it: See the blue note on:http://guides.rails.info/getting_started.html says "Ruby 1.9.1 is not usable because it outright segfaults onRails 3.0, so if you want to use Rails 3 with 1.9.x jump on 1.9.2 for smooth sailing."

Before the Class : OptionalPlease follow the tutorial here :http://guides.rails.info/getting_started.html We will be working on this blog app in the class. Some of the things on this tutorial is out dated for Rails 3.0 beta 4. I will also be explaining things that is described in this tutorial from a different perspective. It usually connects all the dots together and the student will be able to see how all the concepts fit together.